Congrats and Welcome!
Here are a couple of things that I try with problem feeder.
1) I feed live and I feed at night. Just before I go to bed I drop in the prey item and then 1st thing in the morning I check to see if the prey item is gone. If not I remove the item and try again in 3-5 days.
2) I don't interact (play/handle) the snake in question until it gets to a consistent feeding schedule. I only got into the tub to change the water when necessary.
3) I try to feed the same day of the week and same time. This will help to establish a more consistent feeding response. Once established you can adjust to what ever you like. But until then I feel it's what best for the animal.
4) Being 1/5 - 2 years old and being 256 grams is a concern but I think it's more about consistent feeding than anything and not the animal itself. She was probably feed to small of a meal and feed every 2 to 3 weeks, which would explain her size. Once on a consistent feeding schedule with the proper size prey item this will be corrected almost immediately.
5) if none of the above has any positive result I would consider covering the exposed glass on your tank. This would be the last thing I would do and only if all the other changes don't help. It's far down the list of options.
I don't think you have anything to be overly concerned about. She at least had an initial response so we need to build in that, If you have any other questions just let me know. I'd be happy to help anyway I can.
Pete